Troubleshooting DC circuits: if the measured current in a simple series circuit is 0 A (zero), which condition is most likely present?
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Avoltage is too high
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Bresistance is too low
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Ccircuit has a short
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Dcircuit is open
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E—
Answer
Correct Answer: circuit is open
Explanation
Introduction / Context:Recognizing fault types quickly (open vs short) is essential in diagnostics. Zero current often points to a specific failure mode with clear corrective actions.
Given Data / Assumptions:
- DC source present and capable.
- Series path for current must be continuous to allow flow.
- Ohm’s law applies: I = V / R_total.
Concept / Approach:An open circuit breaks the conductive path, making R_total effectively infinite. With finite source voltage, current I approaches zero. In contrast, a short circuit reduces R_total, increasing current drastically rather than dropping it to zero.
Step-by-Step Solution:Zero current observed → consider I = V / R_total.For I → 0 with finite V, R_total must be extremely large → open circuit.Therefore, the most probable cause is a disconnected wire, blown fuse, or open switch.
Verification / Alternative check:Measure voltage across the suspected open. A full source voltage appearing across a break corroborates an open-circuit diagnosis.
Why Other Options Are Wrong:Short: would cause very large current, not zero.Too high voltage or too low resistance: both would increase current, not eliminate it.
Common Pitfalls:Assuming failed source instead of checking continuity; misinterpreting a faulty meter reading when on the wrong range.
Final Answer:circuit is open